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C3P0数据库连接池的java实现

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1、配置准备

  • 导入 jar 包
    • c3p0-0.9.2-pre1.jar
    • mchange-commons-0.2.jar
    • 数据库驱动包, 如：mysql-connector-java-5.1.28-bin.jar
  • 配置文件名称必须叫 c3p0-config.xml
  • 配置文件位置必须在 src 下
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2、配置文件

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <!-- 这是默认配置信息 -->
    <default-config> 
        <!-- 连接四大参数配置 -->
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/mydb3</property>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="user">root</property>
        <property name="password">123</property>
        <!-- 池参数配置 -->
        <!-- 连接池初始化时建立的连接数 默认值是 3 -->  
        <property name="initialPoolSize">3</property>  
        <!-- 连接的最大空闲时间  单位秒 默认是 0- 代表永远不会断开连接  超过设定时间的空闲连接将会断开 -->  
        <property name="maxIdleTime">30</property>  
        <!-- 连接池中拥有的最大连接数 默认值为 15 个 -->  
        <property name="maxPoolSize">20</property>  
        <!-- 连接池中保持的最小连接数  默认值为 3 个-->  
        <property name="minPoolSize">3</property>  
        <!-- 将连接池的连接数保持在 minpoolsize 必须小于 maxIdleTime 设置  默认值为 0 代表不处理  单位秒 -->  
        <property name="maxIdleTimeExcessConnections">15</property>  

<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">default-config</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 专门为oracle提供的配置信息 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">named-config </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="oracle-config"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span> 
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="jdbcUrl"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>jdbc:oracle:oci8:@dataname<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="driverClass"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>oracle.jdbc.driver.OracleDriver<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="user"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>root<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>123<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="acquireIncrement"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>3<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="initialPoolSize"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>10<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="minPoolSize"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>2<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="maxPoolSize"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>10<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">named-config</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>



</c3p0-config>

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3、实现案例

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;

import org.junit.Test;


import com.mchange.v2.c3p0.ComboPooledDataSource;


/**


    

  • 

    c3p0*/
    public class Demo1 {
    /**
    

      

    • 

      代码配置，该配置不需要配置文件
      

      • 

    • 

      @throws PropertyVetoException
      

      • 

    • 

      @throws SQLException
      */
      @Test
      public void fun1() throws PropertyVetoException, SQLException {
      // 创建连接池对象
      ComboPooledDataSource dataSource = new ComboPooledDataSource();
      

      // 对池进行四大参数的配置
      dataSource.setDriverClass("com.mysql.jdbc.Driver");
      dataSource.setJdbcUrl(      "jdbc:mysql://localhost:3306/mydb");
      dataSource.setUser(      "root");
      dataSource.setPassword(      "123");
      

      // 池配置
      dataSource.setAcquireIncrement(5);
      dataSource.setInitialPoolSize(      20);
      dataSource.setMinPoolSize(      2);
      dataSource.setMaxPoolSize(      50);
      

      Connection con = dataSource.getConnection();
      System.out.println(con);
      con.close(); // 该 close() 方法不是关闭连接，而是将连接归还给连接池。
      }
      

      • 

    

    /**
    

      

    • 

      配置文件的默认配置，若代码中同时存在配置，代码中的配置参数优先
      

      • 

    • 

      @throws SQLException
      */
      @Test
      public void fun2() throws SQLException{
      /**
      

        

      • 在创建连接池对象时，这个对象就会自动加载配置文件！不用我们来指定
        */
        ComboPooledDataSource dataSource          = new ComboPooledDataSource();
        • 

      

      Connection con = dataSource.getConnection();
      System.out.println(con);
      con.close();
      }
      

      • 

    

    /**
    

      

    • 

      使用命名配置信息
      

      • 

    • 

      @throws SQLException
      */
      @Test
      public void fun3() throws SQLException{
      /**
      

        

      • 构造器的参数指定命名配置元素的名称！
        • 

      • <named-config name="oracle-config">
        */
        ComboPooledDataSource dataSource          = new ComboPooledDataSource("oracle-config");
        • 

      

      Connection con = dataSource.getConnection();
      System.out.println(con);
      con.close();
      }
      }